INTERNATIONAL TELECOMMUNICATION UNION
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`CCITT
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`THE INTERNATIONAL
`TELEGRAPH AND TELEPHONE
`CONSULTATIVE COMMITTEE
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`M.770
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`(11/1988)
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`SERIES M: GENERAL MAINTENANCE PRINCIPLES
`Maintenance of international transmission systems and
`telephone circuits – Common channel signalling systems
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`INTER-ADMINISTRATION AGREEMENTS ON
`COMMON CHANNEL SIGNALLING SYSTEM
`No. 7
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`Reedition of CCITT Recommendation M.770 published in
`the Blue Book, Fascicle IV.1 (1988)
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`CISCO SYSTEMS, INC. Ex. 1135 Page 1
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`NOTES
`CCITT Recommendation M.770 was published in Fascicle IV.1 of the Blue Book. This file is an extract from
`1
`the Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, the
`contents of the file are identical to the Blue Book version and copyright conditions remain unchanged (see below).
`2
`In this Recommendation, the expression “Administration” is used for conciseness to indicate both a
`telecommunication administration and a recognized operating agency.
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`© ITU 1988, 2008
`All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written
`permission of ITU.
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`CISCO SYSTEMS, INC. Ex. 1135 Page 2
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`Recommendation M.770
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`INTER-ADMINISTRATION AGREEMENTS ON COMMON CHANNEL
`SIGNALLING SYSTEM No. 7
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`Introduction
`1
`The bringing into service of new telephone circuits and signalling systems requires that a number of
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`agreements be made in advance by the Administrations involved. Such agreements may concern, for exemple:
`–
`routing of circuits (cable, satellite, etc.);
`– mode of operation (incoming, outgoing, both-way);
`–
`circuit designation;
`– order of selection of both-way circuits.
`For common channel signalling systems, a number of agreements are needed in addition to those required for
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`channel-associated signalling systems (e.g., Signalling System R2).
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`This Recommendation explains the principal inter-Administration agreements which must be made in advance
`of opening a Signalling System No. 7 service and is provided as guidance to those Administrations intending to operate
`such a service.
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`Common channel Signalling System No. 7 (SS No. 7)
`2
`Many of the aspects covered by this Recommendation relate to matters contained in the specifications of
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`Signalling System No. 7, as appearing in the Series Q Recommendations [1]. Where appropriate, cross references to
`such Recommendations are given.
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`Recommendations Q.701 [2] and Q.721 [3] provide functional descriptions of the Message Transfer Part
`(MTP) and Telephone User Part (TUP) respectively.
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`The Q.780 [4] Series of Recommendations provide guidance on how to test SS No. 7. (Level 1, 2 and 3).
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`3
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`Aspects of SS No. 7 requiring inter-Administration agreement
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`Signalling links and signalling security arrangements
`3.1
`Signals for a given group of speech circuits between two exchanges may be “associated” (routed on a
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`signalling link between the two exchanges), or “non-associated” (routed on two or more signalling links in tandem,
`involving one or more signal-transfer points) or a mixture of both (Recommendation Q.701, § 3.1.2 [2].
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`Before entering into detailed discussions on the type of signalling security arrangements required, it is
`desirable that the terminal Administrations exchange information on the type and manufacturer of their international
`exchange and the options available within their existing software systems. This information will enable each
`Administration to have an overall view of available signalling security arrangements. It will avoid misunderstandings
`and thus enable rapid progress in establishing detailed arrangements. Subsequently, agreement on the following matters
`will be required:
`i) The use of “associated” and/or “non-associated” modes of signalling.
`ii) The choice of signalling transfer points (STPs) in the case where the “non-associated” mode of signalling
`is used.
`iii) Security measures against signalling network link failure, e.g., the use of load sharing between link sets. If
`load sharing between link sets is to be used, agreement must be reached as to the number of link sets
`involved.
`iv) Alternative routing within the signalling network in the event of failure of a link set, i.e., if load sharing is
`not used, which STPs are available for a given signalling network relation, and the order of selection of
`these. Due regard must be paid to the limitation of the number of STPs in tandem in a given signalling
`network relation (see Recommendation Q.705 § 5) [5].
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`Fascicle IV.1 – Rec. M.770
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`v) The routing of the signalling network links must ensure that the propagation delay of the links is as low as
`possible, and not significantly higher than that of the speech circuits which are served by Signalling
`System No. 7. This is to minimize the initial speech clipping of the verbal answer from the called party.
`The above factors must also be considered in any restoration plans, although the non-availability of links
`may force administrations to accept the possibility of clipping under failure conditions.
`vi) The nature of the signalling network link to be used, e.g., 4.8 kbit/s analogue or 64 kbit/s digital,
`transmission routing, etc.
`vii) The method of error correction to be employed in a given signalling relation, i.e., basic or preventive
`cyclic retransmission (see Recommendation Q.703 § 5) [6].
`viii) Emergency restart conditions. (If there is automatic allocation of signalling terminals or signalling data
`links at the end of a signalling link, it must be ensured that the value (T2) of the timeout is different at each
`end (see Recommendation Q.703, § 7.3 and Q.704, § 3.4.3) [6] and [7]).
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`Mode of signalling
`3.2
`Signalling System No. 7 provides for two basic modes of sending signalling information namely, “en-bloc” or
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`“overlap” (Recommendation Q.724) [8].
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`Signalling network consideration for cross-border traffic
`3.3
`For cross-border traffic between signalling points, a bilateral agreement needs to be made for the routing label
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`assignment of signalling point codes.
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`Two alternative arrangements are described in Recommendation Q.705, § 6 [5]. One arrangement provides for
`signalling points which are handling cross-border traffic to be given signal point codes taken from the international
`numbering plan contained in Recommendation Q.708 [9]. The other provides for these signalling points to be identified
`by common national point codes.
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`Routing label assignment
`3.4
`The routing label is that part of the message label which contains the information necessary to deliver the
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`message to its destination point. It comprises the following (see Recommendation Q.704, § 2.2) [7]:
`– destination point code (DPC);
`– originating point code (DPC);
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`signalling link selection (SLS) field or signalling link code (SLC).
`DPC and OPC labelling will be in accordance with Recommendation Q.708 [9]. However it may be necessary
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`to have a bilateral agreement for the SLS, so that it can be assigned individually to signalling links.
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`Circuit identification code
`3.5
`The circuit identification code (CIC) indicates one speech circuit among those directly interconnecting the
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`destination and the originating points. The allocation of CICs to individual circuits is determined by bilateral agreement
`and/or in accordance with predetermined rules. See Recommendation Q.723, § 2.2.3 [10].
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`Reset of circuit and circuit group messages
`3.6
`In systems which maintain status in memory there may be occasions when the memory becomes mutilated. In
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`such cases the circuits must be reset to the idle condition in both exchanges to make them available for new traffic. Since
`the exchange with mutilated memory does not know whether the circuits are idle, busy outgoing, busy incoming,
`blocked, etc., reset-circuit signals or a circuit group reset should be sent as appropriate for the affected circuits (see
`Recommendation Q.724, § 1.15) [8].
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`Under certain failure conditions however, where a large number of circuits is involved, it is possible that some
`realisations of SS No. 7 terminal equipment will be unable to process the volume of reset messages generated. It is
`necessary, therefore, that Administrations agree bilaterally whether circuit and circuit group messages should both be
`used.
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`Fascicle IV.1 – Rec. M.770
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`Use of the circuit continuity check procedure
`3.7
`Because the SS No. 7 signalling does not pass over the speech path, facilities should be provided for making a
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`continuity check of the speech paths (see Recommendation Q.724, § 1.4) [8].
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`Use of this procedure on a particular circuit will depend on the type of transmission system (e.g., analogue,
`digital, mixed analogue/digital) which is used for the circuit and whether end-to-end supervision is provided on the
`transmission system. It should therefore be bilaterally agreed.
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`Choice of the time slot to be used within the primary order digital path for the signalling link
`3.8
`In the case where time slot 16 is utilized for circuit supervision purposes (see Recommendation Q.33, § A.1)
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`[11], it is necessary to agree bilaterally on which time slot within the primary order digital path should be used for the
`signalling link.
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`Changing from one specification of the signalling system to another
`3.9
`If an Administration changes from one version of the specification of the signalling system to another, distant
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`Administrations should be informed as a precautionary measure before the change takes place since potential
`interworking problems can then be anticipated. It is desirable therefore, that Administrations should be aware of the need
`for, and agree to, this exchange of information.
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`Timing on inter-Administration agreements
`4
`Due to the differing practices and procedures of Administrations no specific timetable for the inter-
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`Administration agreements necessary on SS No. 7 can be offered. However, experience indicates that initial discussions
`between Administrations concerning the implementation of a new common channel signalling system should preferably
`commence about two years prior to the required “ready for service” date.
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`References
`CCITT Recommendation Specification of Signalling System No. 7, Vol. VI, Recommendations Q.701-Q.795.
`CCITT Recommendation Functional description of the signalling system (Message Transfer Part), Vol. VI,
`Recommendation Q.701.
`CCITT Recommendation Functional description of the signalling system (Telephone User part (TUP)),
`Vol. VI, Recommendation Q.721.
`CCITT Recommendation Signalling System No. 7 test specification, general description, Vol. VI,
`Recommendation Q.780.
`CCITT Recommendation Signalling network structure, Vol. VI, Recommendation Q.705.
`CCITT Recommendation Signalling link, Vol. VI, Recommendation Q.703.
`CCITT Recommendation Signalling network functions and messages, Vol. VI, Recommendation Q.704.
`CCITT Recommendation Signalling procedures, Vol. VI, Recommendation Q.724.
`CCITT Recommendation Numbering of international signalling point codes, Vol. VI, Recommendation
`Q.708.
`CCITT Recommendation Formats and codes, Vol. VI, Recommendation Q.723.
`CCITT Recommendation Protection against the effects of faulty transmission on groups of circuits Vol. VI,
`Recommendation Q.33.
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`Fascicle IV.1 – Rec. M.770
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`3
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`[1]
`[2]
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`[3]
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`[4]
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`[5]
`[6]
`[7]
`[8]
`[9]
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`[10]
`[11]
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`Series A
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`Series B
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`Series C
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`ITU-T RECOMMENDATIONS SERIES
`Organization of the work of the ITU-T
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`Means of expression: definitions, symbols, classification
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`General telecommunication statistics
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`Series D
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`General tariff principles
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`Series E
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`Series F
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`Overall network operation, telephone service, service operation and human factors
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`Non-telephone telecommunication services
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`Series G
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`Transmission systems and media, digital systems and networks
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`Series H
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`Audiovisual and multimedia systems
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`Series I
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`Series J
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`Integrated services digital network
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`Transmission of television, sound programme and other multimedia signals
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`Series K
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`Protection against interference
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`Series L
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`Construction, installation and protection of cables and other elements of outside plant
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`Series M
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`international transmission systems, telephone circuits,
`TMN and network maintenance:
`telegraphy, facsimile and leased circuits
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`Series N
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`Series O
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`Series P
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`Maintenance: international sound programme and television transmission circuits
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`Specifications of measuring equipment
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`Telephone transmission quality, telephone installations, local line networks
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`Series Q
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`Switching and signalling
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`Series R
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`Telegraph transmission
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`Telegraph services terminal equipment
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`Terminals for telematic services
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`Telegraph switching
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`Data communication over the telephone network
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`Data networks and open system communications
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`Global information infrastructure and Internet protocol aspects
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`Languages and general software aspects for telecommunication systems
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`Series S
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`Series T
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`Series U
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`Series V
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`Series X
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`Series Y
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`Series Z
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`Printed in Switzerland
`Geneva, 2008
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`CISCO SYSTEMS, INC. Ex. 1135 Page 8